const S0: [u8; 256] = [
    0x3E, 0x72, 0x5B, 0x47, 0xCA, 0xE0, 0x00, 0x33, 0x04, 0xD1, 0x54, 0x98, 0x09, 0xB9, 0x6D, 0xCB,
    0x7B, 0x1B, 0xF9, 0x32, 0xAF, 0x9D, 0x6A, 0xA5, 0xB8, 0x2D, 0xFC, 0x1D, 0x08, 0x53, 0x03, 0x90,
    0x4D, 0x4E, 0x84, 0x99, 0xE4, 0xCE, 0xD9, 0x91, 0xDD, 0xB6, 0x85, 0x48, 0x8B, 0x29, 0x6E, 0xAC,
    0xCD, 0xC1, 0xF8, 0x1E, 0x73, 0x43, 0x69, 0xC6, 0xB5, 0xBD, 0xFD, 0x39, 0x63, 0x20, 0xD4, 0x38,
    0x76, 0x7D, 0xB2, 0xA7, 0xCF, 0xED, 0x57, 0xC5, 0xF3, 0x2C, 0xBB, 0x14, 0x21, 0x06, 0x55, 0x9B,
    0xE3, 0xEF, 0x5E, 0x31, 0x4F, 0x7F, 0x5A, 0xA4, 0x0D, 0x82, 0x51, 0x49, 0x5F, 0xBA, 0x58, 0x1C,
    0x4A, 0x16, 0xD5, 0x17, 0xA8, 0x92, 0x24, 0x1F, 0x8C, 0xFF, 0xD8, 0xAE, 0x2E, 0x01, 0xD3, 0xAD,
    0x3B, 0x4B, 0xDA, 0x46, 0xEB, 0xC9, 0xDE, 0x9A, 0x8F, 0x87, 0xD7, 0x3A, 0x80, 0x6F, 0x2F, 0xC8,
    0xB1, 0xB4, 0x37, 0xF7, 0x0A, 0x22, 0x13, 0x28, 0x7C, 0xCC, 0x3C, 0x89, 0xC7, 0xC3, 0x96, 0x56,
    0x07, 0xBF, 0x7E, 0xF0, 0x0B, 0x2B, 0x97, 0x52, 0x35, 0x41, 0x79, 0x61, 0xA6, 0x4C, 0x10, 0xFE,
    0xBC, 0x26, 0x95, 0x88, 0x8A, 0xB0, 0xA3, 0xFB, 0xC0, 0x18, 0x94, 0xF2, 0xE1, 0xE5, 0xE9, 0x5D,
    0xD0, 0xDC, 0x11, 0x66, 0x64, 0x5C, 0xEC, 0x59, 0x42, 0x75, 0x12, 0xF5, 0x74, 0x9C, 0xAA, 0x23,
    0x0E, 0x86, 0xAB, 0xBE, 0x2A, 0x02, 0xE7, 0x67, 0xE6, 0x44, 0xA2, 0x6C, 0xC2, 0x93, 0x9F, 0xF1,
    0xF6, 0xFA, 0x36, 0xD2, 0x50, 0x68, 0x9E, 0x62, 0x71, 0x15, 0x3D, 0xD6, 0x40, 0xC4, 0xE2, 0x0F,
    0x8E, 0x83, 0x77, 0x6B, 0x25, 0x05, 0x3F, 0x0C, 0x30, 0xEA, 0x70, 0xB7, 0xA1, 0xE8, 0xA9, 0x65,
    0x8D, 0x27, 0x1A, 0xDB, 0x81, 0xB3, 0xA0, 0xF4, 0x45, 0x7A, 0x19, 0xDF, 0xEE, 0x78, 0x34, 0x60,
];

const S1: [u8; 256] = [
    0x55, 0xC2, 0x63, 0x71, 0x3B, 0xC8, 0x47, 0x86, 0x9F, 0x3C, 0xDA, 0x5B, 0x29, 0xAA, 0xFD, 0x77,
    0x8C, 0xC5, 0x94, 0x0C, 0xA6, 0x1A, 0x13, 0x00, 0xE3, 0xA8, 0x16, 0x72, 0x40, 0xF9, 0xF8, 0x42,
    0x44, 0x26, 0x68, 0x96, 0x81, 0xD9, 0x45, 0x3E, 0x10, 0x76, 0xC6, 0xA7, 0x8B, 0x39, 0x43, 0xE1,
    0x3A, 0xB5, 0x56, 0x2A, 0xC0, 0x6D, 0xB3, 0x05, 0x22, 0x66, 0xBF, 0xDC, 0x0B, 0xFA, 0x62, 0x48,
    0xDD, 0x20, 0x11, 0x06, 0x36, 0xC9, 0xC1, 0xCF, 0xF6, 0x27, 0x52, 0xBB, 0x69, 0xF5, 0xD4, 0x87,
    0x7F, 0x84, 0x4C, 0xD2, 0x9C, 0x57, 0xA4, 0xBC, 0x4F, 0x9A, 0xDF, 0xFE, 0xD6, 0x8D, 0x7A, 0xEB,
    0x2B, 0x53, 0xD8, 0x5C, 0xA1, 0x14, 0x17, 0xFB, 0x23, 0xD5, 0x7D, 0x30, 0x67, 0x73, 0x08, 0x09,
    0xEE, 0xB7, 0x70, 0x3F, 0x61, 0xB2, 0x19, 0x8E, 0x4E, 0xE5, 0x4B, 0x93, 0x8F, 0x5D, 0xDB, 0xA9,
    0xAD, 0xF1, 0xAE, 0x2E, 0xCB, 0x0D, 0xFC, 0xF4, 0x2D, 0x46, 0x6E, 0x1D, 0x97, 0xE8, 0xD1, 0xE9,
    0x4D, 0x37, 0xA5, 0x75, 0x5E, 0x83, 0x9E, 0xAB, 0x82, 0x9D, 0xB9, 0x1C, 0xE0, 0xCD, 0x49, 0x89,
    0x01, 0xB6, 0xBD, 0x58, 0x24, 0xA2, 0x5F, 0x38, 0x78, 0x99, 0x15, 0x90, 0x50, 0xB8, 0x95, 0xE4,
    0xD0, 0x91, 0xC7, 0xCE, 0xED, 0x0F, 0xB4, 0x6F, 0xA0, 0xCC, 0xF0, 0x02, 0x4A, 0x79, 0xC3, 0xDE,
    0xA3, 0xEF, 0xEA, 0x51, 0xE6, 0x6B, 0x18, 0xEC, 0x1B, 0x2C, 0x80, 0xF7, 0x74, 0xE7, 0xFF, 0x21,
    0x5A, 0x6A, 0x54, 0x1E, 0x41, 0x31, 0x92, 0x35, 0xC4, 0x33, 0x07, 0x0A, 0xBA, 0x7E, 0x0E, 0x34,
    0x88, 0xB1, 0x98, 0x7C, 0xF3, 0x3D, 0x60, 0x6C, 0x7B, 0xCA, 0xD3, 0x1F, 0x32, 0x65, 0x04, 0x28,
    0x64, 0xBE, 0x85, 0x9B, 0x2F, 0x59, 0x8A, 0xD7, 0xB0, 0x25, 0xAC, 0xAF, 0x12, 0x03, 0xE2, 0xF2,
];

const D: [u16; 16] = [
    0x44D7, 0x26BC, 0x626B, 0x135E, 0x5789, 0x35E2, 0x7135, 0x09AF, 0x4D78, 0x2F13, 0x6BC4, 0x1AF1,
    0x5E26, 0x3C4D, 0x789A, 0x47AC,
];

struct Zuc {
    s: [u32; 16],
    r1: u32,
    r2: u32,
    x: [u32; 4],
}

impl Zuc {
    fn new(k: &[u8], iv: &[u8]) -> Self {
        let mut s = [0; 16];
        for i in 0..16 {
            s[i] = make_u31(k[i] as u32, D[i] as u32, iv[i] as u32);
        }
        let mut zuc = Zuc {
            s,
            r1: 0,
            r2: 0,
            x: [0; 4],
        };

        for _ in 0..32 {
            zuc.bit_reconstruction();
            let w = zuc.f();
            zuc.lfsr_with_initialization_mode(w >> 1);
        }
        zuc.generate_keystream(1);
        zuc
    }

    fn bit_reconstruction(&mut self) {
        self.x[0] = ((self.s[15] & 0x7FFF8000) << 1) | (self.s[14] & 0xFFFF);
        self.x[1] = ((self.s[11] & 0xFFFF) << 16) | (self.s[9] >> 15);
        self.x[2] = ((self.s[7] & 0xFFFF) << 16) | (self.s[5] >> 15);
        self.x[3] = ((self.s[2] & 0xFFFF) << 16) | (self.s[0] >> 15);
    }

    fn f(&mut self) -> u32 {
        let w = (self.x[0] ^ self.r1).wrapping_add(self.r2);
        let w1 = self.r1.wrapping_add(self.x[1]);
        let w2 = self.r2 ^ self.x[2];

        let u = l1((w1 << 16) | (w2 >> 16));
        let v = l2((w2 << 16) | (w1 >> 16));

        self.r1 = sbox(u);
        self.r2 = sbox(v);
        w
    }

    fn lfsr_with_initialization_mode(&mut self, u: u32) {
        let v = self.s[0];
        let v = add31(v, rot31(self.s[0], 8));
        let v = add31(v, rot31(self.s[4], 20));
        let v = add31(v, rot31(self.s[10], 21));
        let v = add31(v, rot31(self.s[13], 17));
        let v = add31(v, rot31(self.s[15], 15));

        let mut s16 = add31(v, u);

        if s16 == 0 {
            s16 = 2147483647;
        }
        for i in 0..15 {
            self.s[i] = self.s[i + 1];
        }
        self.s[15] = s16;
    }

    fn lfsr_with_work_mode(&mut self) {
        let v = self.s[0];
        let v = add31(v, rot31(self.s[0], 8));
        let v = add31(v, rot31(self.s[4], 20));
        let v = add31(v, rot31(self.s[10], 21));
        let v = add31(v, rot31(self.s[13], 17));
        let mut s16 = add31(v, rot31(self.s[15], 15));
        if s16 == 0 {
            s16 = 2147483647;
        }
        for i in 0..15 {
            self.s[i] = self.s[i + 1];
        }
        self.s[15] = s16;
    }

    fn generate_keystream(&mut self, n: usize) -> Vec<u32> {
        let mut keystream = vec![];
        for _ in 0..n {
            self.bit_reconstruction();
            let z = self.f() ^ self.x[3];
            self.lfsr_with_work_mode();
            keystream.push(z);
        }
        keystream
    }

    pub fn zuc_encrypt(&mut self, input: &[u8]) -> Vec<u8> {
        let padded_len = (input.len() / 4 + 1) * 4;
        let mut buf = Vec::from(input);
        let padded = (padded_len - input.len()) as u8;
        for _ in input.len()..padded_len {
            buf.push(padded);
        }
        let key_stream = self.generate_keystream(padded_len / 4);
        for (i, key) in key_stream.iter().enumerate() {
            let s = i * 4;
            [buf[s], buf[s + 1], buf[s + 2], buf[s + 3]] =
                (u32::from_be_bytes([buf[s], buf[s + 1], buf[s + 2], buf[s + 3]]) ^ key)
                    .to_be_bytes();
        }
        buf
    }
}

#[inline]
fn make_u32(a: u32, b: u32, c: u32, d: u32) -> u32 {
    a << 24 | b << 16 | c << 8 | d
}

#[inline]
fn make_u31(k: u32, d: u32, iv: u32) -> u32 {
    k << 23 | d << 8 | iv
}

#[inline]
fn sbox(x: u32) -> u32 {
    make_u32(
        S0[(x >> 24) as usize] as u32,
        S1[((x >> 16) & 0xFF) as usize] as u32,
        S0[((x >> 8) & 0xFF) as usize] as u32,
        S1[(x & 0xFF) as usize] as u32,
    )

    // let idx = x.to_be_bytes();
    // let (y0, y1, y2, y3) = (
    //     S0[idx[0] as usize], S1[idx[1] as usize], S0[idx[2] as usize], S1[idx[3] as usize]
    // );
    // u32::from_be_bytes([y0, y1, y2, y3])
}

#[inline]
fn rot31(a: u32, k: u32) -> u32 {
    ((a << k) | (a >> (31 - k))) & 0x7FFFFFFF
}

#[inline]
fn add31(a: u32, b: u32) -> u32 {
    let c = a.wrapping_add(b);
    (c & 0x7FFFFFFF).wrapping_add(c >> 31)
}

fn l1(x: u32) -> u32 {
    x ^ x.rotate_left(2) ^ x.rotate_left(10) ^ x.rotate_left(18) ^ x.rotate_left(24)
}

fn l2(x: u32) -> u32 {
    x ^ x.rotate_left(8) ^ x.rotate_left(14) ^ x.rotate_left(22) ^ x.rotate_left(30)
}

pub fn encryption(input: String) -> String {
    let key = [0u8; 16];
    let iv = [1u8; 16];
    let mut zuc = Zuc::new(&key, &iv);

    let res = zuc.zuc_encrypt(input.as_bytes());
    use base64::engine::general_purpose::STANDARD;
    use base64::Engine;

    STANDARD.encode(res)
}
